drop table stu;
create table stu(
	id number ,
	uname varchar2(40),
	password varchar2(40),
	sex char(1) check (sex in(0,1)),
	studentId varchar2(40),
	groupId varchar2(40)
);

alter table stu add constraint pk_stuid primary key(id);

create sequence stu_id
increment by 1
start with 1
nomaxvalue
nocycle
nocache;

select * from stu where id=stu_id.nextval;

delete stu where id=11;

select * from stu ;